Who Cares About Equilibrium?

Abstract

Drilling has yielded much information about the subsurface geology of geothermal systems. It has also opened insights into the evolution of large tectonically and volcanically active regions, for example the Taupo Volcanic Zone (Milicich et al, 2013; Wilson et al, 2010). However, active geothermal systems are also large natural laboratories. Some of their characteristics are revealed through fieldwork, examining cores and cuttings, output and production data, measuring down hole temperatures and pressures, analyzing thermal fluids and reservoir modeling. Our knowledge of processes that affect the physical, chemical and mineralogical properties of rocks and thermal fluids has increased several fold since Fenner’s (1936) brave but dangerous exploratory drilling in Yellowstone National Park in the 1930’s. His pioneering research was greatly extended after the War when successful exploratory, production and research drilling was begun at the Wairakei field (Thain and Carey, 2009 ) and later at other geothermal prospects in New Zealand, Iceland, USA, Mexico, Japan, Indonesia, the Philippines and Kenya.